A method and a device for operating an internal combustion engine having multiple cylinders is discussed in German patent application, which has application number 10 2005 047 446 and which was not published previously, in which the cylinders each include an intake valve and an exhaust valve and a characteristic quantity for a suction performance of a cylinder of the internal combustion engine is ascertained. If the value for the suction performance obtained for the characteristic quantity is compared with a setpoint value, the function of the suction of the cylinder may be diagnosed as a function of the result of the comparison. It is readily possible in this way with the help of the characteristic quantity for the suction performance of the cylinder to check on whether or not the suction of the cylinder is defective. Suction performance is influenced among other things as a function of the phase angle and the lift of the valve lift diagram of the intake valve(s) of the particular cylinder and the imperviousness of the combustion chamber of the particular cylinder, in particular with regard to the intake and exhaust valves and the piston rings.